.anima-change-bg {
  fill: #a00;
  stroke: #a00;
  animation-duration: 1s;
  animation-name: change-bg;
  animation-iteration-count: infinite;
}

@keyframes change-bg {
  0%  {
    fill: #a00;
    stroke: #a00;
  }
  50% {
    fill: #00ff00;
    stroke: #00ff00;
  }
  100%  {
    fill: #a00;
    stroke: #a00;
  }
}